Fixed a bug where the notifications would close on back

When the panel collapsing was aborted or couldn't close
because we were tracking, then the panel wouldn't be
focusable anymore so it wouldn't handle the back pressed
for example.

Change-Id: If88c0b08301dccf8c2dcd79df5239e12fc83cce5
Test: click back while expanding, click back again when expanding finished, observe collapsing.
Fixes: 33260393